The electronic industry has been striving towards the miniaturization and shrinking of transistor dimensions in commercial chips. In recent years, efforts have been made towards the research and development of nanoscale wires and devices. Nanotube, in particular, carbon nanotube (CNT) has been a promising material for incorporation into electronic circuits due to its superior transport property and nanoscale dimension. The hybrid technology combining CNT with the current silicon metal-oxide semiconductor (MOS) technology and new nanoscale materials is another promising CNT application.
A CNT can be categorized as a single-walled CNT (SWCNT) or a multi-walled CNT (WMCNT). Most single-walled CNT have a diameter of close to 1 nanometer, with a tube length that can be many thousands of times longer. The structure of a SWCNT can be conceptualized as a thin layer of graphite called graphene wrapping into a seamless cylinder. On the other hand, MWCNT consist of multiple layers of graphite rolled in on themselves to form a tube shape. The SWCNT exhibit some important electric properties that are not shared by the multi-walled carbon nanotube (MWNT) variants, they are the most likely candidate for miniaturizing electronics beyond the micro electromechanical scale.
CNTs can be chemically modified e.g., various molecules may be attached to the CNTs with an aim to give the CNT new functional properties and/or create biological and chemical sensors including, for example, DNA separation, protein recognition, and drug delivery capabilities).
Applications of CNTs include electron emitters for display, electron beam source and X-ray sources. CNTs may also be modified to better suit an application such as sensor application. For example, various molecules may be attached to CNTs to give the CNT new functional properties, or to create the biological and chemical sensors. The new function properties may include DNA separation, protein recognition and drug delivery capabilities. For these potential applications, CNTs need to be grown at a low temperatures on substrates with low melting points.
Another promising application of CNT is related to the substitution of metallic interconnects in the integrated circuits (ICs) distributing signals, power, ground supply lines and other elements for systems on a chip.